/****************************************************************************
 * arch/arm/src/sama5/sam_rtc.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <nuttx/arch.h>
#include <nuttx/irq.h>

#include <time.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/arch.h>
#include <nuttx/irq.h>
#include <nuttx/wqueue.h>

#include <arch/board/board.h>

#include "arm_arch.h"
#include "sam_rtc.h"

#ifdef CONFIG_RTC

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* Configuration ************************************************************/

/* This RTC implementation supports only date/time RTC hardware */

#ifndef CONFIG_RTC_DATETIME
#  error "CONFIG_RTC_DATETIME must be set to use this driver"
#endif

#ifdef CONFIG_RTC_HIRES
#  error "CONFIG_RTC_HIRES must NOT be set with this driver"
#endif

#if defined(CONFIG_RTC_ALARM) && !defined(CONFIG_SCHED_WORKQUEUE)
#  error CONFIG_RTC_ALARM requires CONFIG_SCHED_WORKQUEUE
#endif

#define RTC_MAGIC 0xdeadbeef

/****************************************************************************
 * Private Data
 ****************************************************************************/

/* Callback to use when the alarm expires */

#ifdef CONFIG_RTC_ALARM
static alarmcb_t g_alarmcb;
struct work_s g_alarmwork;
#endif

/****************************************************************************
 * Public Data
 ****************************************************************************/

/* g_rtc_enabled is set true after the RTC has successfully initialized */

volatile bool g_rtc_enabled = false;

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: rtc_dumpregs
 *
 * Description:
 *    Disable RTC write protection
 *
 * Input Parameters:
 *   None
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

#ifdef CONFIG_DEBUG_RTC_INFO
static void rtc_dumpregs(FAR const char *msg)
{
  rtcinfo("%s:\n", msg);
  rtcinfo("      CR: %08x\n", getreg32(SAM_RTC_CR));
  rtcinfo("      MR: %08x\n", getreg32(SAM_RTC_MR));
  rtcinfo("    TIMR: %08x\n", getreg32(SAM_RTC_TIMR));
  rtcinfo("    CALR: %08x\n", getreg32(SAM_RTC_CALR));
  rtcinfo("  TIMALR: %08x\n", getreg32(SAM_RTC_TIMALR));
  rtcinfo("  CALALR: %08x\n", getreg32(SAM_RTC_CALALR));
  rtcinfo("      SR: %08x\n", getreg32(SAM_RTC_SR));
  rtcinfo("     IMR: %08x\n", getreg32(SAM_RTC_IMR));
  rtcinfo("     VER: %08x\n", getreg32(SAM_RTC_VER));
}
#else
#  define rtc_dumpregs(msg)
#endif

/****************************************************************************
 * Name: rtc_dumptime
 *
 * Description:
 *    Disable RTC write protection
 *
 * Input Parameters:
 *   None
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

#ifdef CONFIG_DEBUG_RTC_INFO
static void rtc_dumptime(FAR struct tm *tp, FAR const char *msg)
{
  rtcinfo("%s:\n", msg);
  rtcinfo("  tm_sec: %08x\n", tp->tm_sec);
  rtcinfo("  tm_min: %08x\n", tp->tm_min);
  rtcinfo(" tm_hour: %08x\n", tp->tm_hour);
  rtcinfo(" tm_mday: %08x\n", tp->tm_mday);
  rtcinfo("  tm_mon: %08x\n", tp->tm_mon);
  rtcinfo(" tm_year: %08x\n", tp->tm_year);
}
#else
#  define rtc_dumptime(tp, msg)
#endif

/****************************************************************************
 * Name: rtc_bin2bcd
 *
 * Description:
 *   Converts a 2 digit binary to BCD format
 *
 * Input Parameters:
 *   value - The byte to be converted.
 *
 * Returned Value:
 *   The value in BCD representation
 *
 ****************************************************************************/

static uint32_t rtc_bin2bcd(int value)
{
  uint32_t msbcd = 0;

  while (value >= 10)
    {
      msbcd++;
      value -= 10;
    }

  return (msbcd << 4) | value;
}

/****************************************************************************
 * Name: rtc_bin2bcd
 *
 * Description:
 *   Convert from 2 digit BCD to binary.
 *
 * Input Parameters:
 *   value - The BCD value to be converted.
 *
 * Returned Value:
 *   The value in binary representation
 *
 ****************************************************************************/

static int rtc_bcd2bin(uint32_t value)
{
  uint32_t tens = (value >> 4) * 10;
  return (int)(tens + (value & 0x0f));
}

/****************************************************************************
 * Name: rtc_worker
 *
 * Description:
 *    Perform alarm callback
 *
 * Input Parameters:
 *   Standard work callbacks
 *
 * Returned Value:
 *   Zero (OK) on success; A negated errno value on failure.
 *
 ****************************************************************************/

#ifdef CONFIG_RTC_ALARM
static void rtc_worker(FAR void *arg)
{
  /* Sample once (atomically) */

  alarmcb_t alarmcb = g_alarmcb;

  /* Is there a subscriber to the alarm? */

  if (alarmcb)
    {
      /* Yes.. perform the callback */

      alarmcb();
    }
}
#endif

/****************************************************************************
 * Name: rtc_interrupt
 *
 * Description:
 *    RTC interrupt service routine
 *
 * Input Parameters:
 *   irq - The IRQ number that generated the interrupt
 *   context - Architecture specific register save information.
 *
 * Returned Value:
 *   Zero (OK) on success; A negated errno value on failure.
 *
 ****************************************************************************/

#ifdef CONFIG_RTC_ALARM
static int rtc_interrupt(int irq, void *context, FAR void *arg)
{
  int ret;

  /* Schedule the callback to occur on the low-priority worker thread */

  DEBUGASSERT(work_available(&g_alarmwork));
  ret = work_queue(LPWORK, &g_alarmwork, rtc_worker, NULL, 0);
  if (ret < 0)
    {
      rtcerr("ERROR: work_queue failed: %d\n", ret);
    }

  /* Disable any further alarm interrupts */

  putreg32(RTC_IDR_ALRDIS, SAM_RTC_IDR);

  /* Clear any pending alarm interrupts */

  putreg32(RTC_SCCR_ALRCLR, SAM_RTC_SCCR);
  return OK;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_rtc_initialize
 *
 * Description:
 *   Initialize the hardware RTC per the selected configuration.  This
 *   function is called once during the OS initialization sequence
 *
 * Input Parameters:
 *   None
 *
 * Returned Value:
 *   Zero (OK) on success; a negated errno on failure
 *
 ****************************************************************************/

int up_rtc_initialize(void)
{
  uint32_t ver;

  rtc_dumpregs("On reset");

  /* No clocking setup need be performed.
   * The Real-time Clock is continuously clocked at 32768 Hz (SCLK).
   * The Power Management Controller has no effect on RTC behavior.
   */

  /* Set the 24 hour format */

  putreg32(0, SAM_RTC_MR);

  /* Has the RTC been initialized? */

  ver = getreg32(SAM_RTC_VER);
  g_rtc_enabled = ((ver & (RTC_VER_NVTIM | RTC_VER_NVCAL)) == 0);

#ifdef CONFIG_RTC_ALARM
  /* Then attach the ALARM interrupt handler */

  irq_attach(SAM_PID_SYS, rtc_interrupt, NULL);

  /* Should RTC alarm interrupt be enabled at the peripheral?  Let's
   * assume so for now.  Let's say yes if the time is valid and a valid
   * alarm has been programmed.
   */

  if (g_rtc_enabled && (ver & (RTC_VER_NVTIMALR | RTC_VER_NVCALALR)) == 0)
    {
      /* Enable the alarm interrupt at the RTC */

      putreg32(RTC_IER_ALREN, SAM_RTC_IER);
    }
  else
    {
      /* Disable the alarm interrupt at the RTC */

      putreg32(RTC_IDR_ALRDIS, SAM_RTC_IDR);
    }

  /* Enable SYSC interrupts at the AIC in any event */

  up_enable_irq(SAM_PID_SYS);

#endif

  rtc_dumpregs("After Initialization");
  return OK;
}

/****************************************************************************
 * Name: up_rtc_getdatetime
 *
 * Description:
 *   Get the current date and time from the date/time RTC.  This interface
 *   is only supported by the date/time RTC hardware implementation.
 *   It is used to replace the system timer.  It is only used by the RTOS
 *   during initialization to set up the system time when CONFIG_RTC and
 *   CONFIG_RTC_DATETIME are selected (and CONFIG_RTC_HIRES is not).
 *
 *   NOTE:
 *   Some date/time RTC hardware is capability of sub-second accuracy.
 *   That sub-second accuracy is lost in this interface.  However, since
 *   the system time is reinitialized on each power-up/reset, there will
 *   be no timing inaccuracy in the long run.
 *
 * Input Parameters:
 *   tp - The location to return the high resolution time value.
 *
 * Returned Value:
 *   Zero (OK) on success; a negated errno on failure
 *
 ****************************************************************************/

int up_rtc_getdatetime(FAR struct tm *tp)
{
  uint32_t timr;
  uint32_t calr;
  uint32_t cent;
  uint32_t year;
  uint32_t tmp;

  /* Sample the data time registers.
   * There is a race condition here... If we sample the time just before
   * midnight on December 31, the date could be wrong because the day rolled
   * over while were sampling.
   */

  do
    {
      calr  = getreg32(SAM_RTC_CALR);
      timr  = getreg32(SAM_RTC_TIMR);
      tmp   = getreg32(SAM_RTC_CALR);
    }
  while (tmp != calr);

  rtc_dumpregs("Reading Time");

  /* Convert the RTC time register fields to struct tm format.
   *
   *   struct tm       TIMR register
   *   tm_sec    0-61* SEC    (0-59)
   *   tm_min    0-59  MIN    (0-59)
   *   tm_hour   0-23  HOUR   (0-23)
   *
   *  *To allow for leap seconds.  But these never actually happen.
   */

  tmp = (timr & RTC_TIMR_SEC_MASK) >> RTC_TIMR_SEC_SHIFT;
  tp->tm_sec = rtc_bcd2bin(tmp);

  tmp = (timr & RTC_TIMR_MIN_MASK) >> RTC_TIMR_MIN_SHIFT;
  tp->tm_min = rtc_bcd2bin(tmp);

  tmp = (timr & RTC_TIMR_HOUR_MASK) >> RTC_TIMR_HOUR_SHIFT;
  tp->tm_hour = rtc_bcd2bin(tmp);

  /* Convert the RTC date register fields to struct tm format.
   *
   *   struct tm       TIMR register
   *   tm_mday   1-31  DATE   (1-31)
   *   tm_wday   0-6   DAY    (1-7)  **
   *   tm_mon    0-11  MONTH: (1-12)
   *   tm_year   *     YEAR   (0-99)
   *                   CENT   (19-20)
   *
   *  *Years since 1900
   * **Day of the week is not supported
   */

  tmp  = (calr & RTC_CALR_DATE_MASK) >> RTC_CALR_DATE_SHIFT;
  tp->tm_mday = rtc_bcd2bin(tmp);

  tmp  = (calr & RTC_CALR_MONTH_MASK) >> RTC_CALR_MONTH_SHIFT;
  tp->tm_mon = rtc_bcd2bin(tmp) - 1;

  tmp  = (calr & RTC_CALR_CENT_MASK) >> RTC_CALR_CENT_SHIFT;
  cent =  rtc_bcd2bin(tmp);
  tmp  = (calr & RTC_CALR_YEAR_MASK) >> RTC_CALR_YEAR_SHIFT;
  year =  rtc_bcd2bin(tmp);
  tp->tm_year = cent * 100 + year - 1900;

  rtc_dumptime(tp, "Returning");
  return OK;
}

/****************************************************************************
 * Name: up_rtc_settime
 *
 * Description:
 *   Set the RTC to the provided time.
 *   All RTC implementations must be able to set their time based on a
 *   standard timespec.
 *
 * Input Parameters:
 *   tp - the time to use
 *
 * Returned Value:
 *   Zero (OK) on success; a negated errno on failure
 *
 ****************************************************************************/

int up_rtc_settime(FAR const struct timespec *tp)
{
  FAR struct tm newtime;
  uint32_t regval;
  uint32_t timr;
  uint32_t calr;
  uint32_t cent;
  uint32_t year;

  /* Break out the time values
   * (note that the time is set only to units of seconds)
   */

  gmtime_r(&tp->tv_sec, &newtime);
  rtc_dumptime(&newtime, "Setting time");

  /* Then write the broken out values to the RTC */

  /* Convert the struct tm format to RTC time register fields.
   *
   *   struct tm       TIMR register
   *   tm_sec    0-61* SEC    (0-59)
   *   tm_min    0-59  MIN    (0-59)
   *   tm_hour   0-23  HOUR   (0-23)
   *
   *  *To allow for leap seconds.  But these never actually happen.
   */

  timr  = (rtc_bin2bcd(newtime.tm_sec)  << RTC_TIMR_SEC_SHIFT)  &
            RTC_TIMR_SEC_MASK;
  timr |= (rtc_bin2bcd(newtime.tm_min)  << RTC_TIMR_MIN_SHIFT)  &
            RTC_TIMR_MIN_MASK;
  timr |= (rtc_bin2bcd(newtime.tm_hour) << RTC_TIMR_HOUR_SHIFT) &
            RTC_TIMR_HOUR_MASK;

  /* Convert the struct tm format to RTC date register fields.
   *
   *   struct tm       CALR register
   *   tm_mday   1-31  DATE   (1-31)
   *   tm_wday   0-6   DAY    (1-7)  **
   *   tm_mon    0-11  MONTH: (1-12)
   *   tm_year   *     YEAR   (0-99)
   *                   CENT   (19-20)
   *
   *  *Years since 1900
   * **Day of the week is not supported.  Set to Monday.
   */

  calr  = (rtc_bin2bcd(newtime.tm_mday)  << RTC_CALR_DATE_SHIFT)  &
              RTC_CALR_DATE_MASK;
  calr |= (rtc_bin2bcd(1)                << RTC_CALR_DAY_SHIFT)   &
              RTC_CALR_DAY_MASK;
  calr |= (rtc_bin2bcd(newtime.tm_mon + 1) << RTC_CALR_MONTH_SHIFT) &
              RTC_CALR_MONTH_MASK;

  cent  = newtime.tm_year / 100 + 19;
  year  = newtime.tm_year % 100;

  calr |= (rtc_bin2bcd(year)             << RTC_CALR_YEAR_SHIFT) &
               RTC_CALR_YEAR_MASK;
  calr |= (rtc_bin2bcd(cent)             << RTC_CALR_CENT_SHIFT) &
               RTC_CALR_CENT_MASK;

  /* Stop RTC time and date counting */

  regval  = getreg32(SAM_RTC_CR);
  regval |= (RTC_CR_UPDTIM | RTC_CR_UPDCAL);
  putreg32(regval, SAM_RTC_CR);

  /* Wait until the RTC has stopped so that we can update the time */

  while ((getreg32(SAM_RTC_SR) & RTC_SR_ACKUPD) != RTC_SR_ACKUPD);

  /* Clear the ACKUPD bit in the status register */

  putreg32(RTC_SCCR_ACKCLR, SAM_RTC_SCCR);

  /* Set the new date */

  putreg32(calr, SAM_RTC_CALR);

  /* Write the new time */

  putreg32(timr, SAM_RTC_TIMR);

  /* Resume RTC date/time counting */

  regval  = getreg32(SAM_RTC_CR);
  regval &= ~(RTC_CR_UPDTIM | RTC_CR_UPDCAL);
  putreg32(regval, SAM_RTC_CR);

  /* Clear the SEC status in the SR */

  regval = getreg32(SAM_RTC_SCCR);
  regval = RTC_SCCR_SECCLR;
  putreg32(regval, SAM_RTC_SCCR);

  /* The RTC should now be enabled */

  g_rtc_enabled = ((getreg32(SAM_RTC_VER) &
                   (RTC_VER_NVTIM | RTC_VER_NVCAL)) == 0);
  DEBUGASSERT(g_rtc_enabled);

  rtc_dumpregs("New time setting");
  return OK;
}

/****************************************************************************
 * Name: sam_rtc_setalarm
 *
 * Description:
 *   Set up an alarm.
 *   Up to two alarms can be supported (ALARM A and ALARM B).
 *
 * Input Parameters:
 *   tp - the time to set the alarm
 *   callback - the function to call when the alarm expires.
 *
 * Returned Value:
 *   Zero (OK) on success; a negated errno on failure
 *
 ****************************************************************************/

#ifdef CONFIG_RTC_ALARM
int sam_rtc_setalarm(FAR const struct timespec *tp, alarmcb_t callback)
{
  FAR struct tm newalarm;
  irqstate_t flags;
  uint32_t timalr;
  uint32_t calalr;
  int ret = -EBUSY;

  /* Is there already something waiting on the ALARM? */

  flags = enter_critical_section();
  if (g_alarmcb == NULL)
    {
      /* No.. Save the callback function pointer */

      g_alarmcb = callback;

      /* Clear any pending alarm interrupts */

      putreg32(RTC_SCCR_ALRCLR, SAM_RTC_SCCR);

      /* Break out the time values (note that the time is set only to units
       * of seconds)
       */

      gmtime_r(&tp->tv_sec, &newalarm);
      rtc_dumptime(&newalarm, "Setting alarm");

      /* Then write the broken out values to the RTC */

      /* Convert the struct tm format to RTC time register fields.
       *
       *   struct tm       TIMALR register
       *   tm_sec    0-61* SEC    (0-59)
       *   tm_min    0-59  MIN    (0-59)
       *   tm_hour   0-23  HOUR   (0-23)
       *
       *  *To allow for leap seconds.  But these never actually happen.
       */

      timalr  = (rtc_bin2bcd(newalarm.tm_sec)  << RTC_TIMALR_SEC_SHIFT)  &
                      RTC_TIMALR_SEC_MASK;
      timalr |= (rtc_bin2bcd(newalarm.tm_min)  << RTC_TIMALR_MIN_SHIFT)  &
                      RTC_TIMALR_MIN_MASK;
      timalr |= (rtc_bin2bcd(newalarm.tm_hour) << RTC_TIMALR_HOUR_SHIFT) &
                      RTC_TIMALR_HOUR_MASK;
      timalr |= (RTC_TIMALR_SECEN | RTC_TIMALR_MINEN | RTC_TIMALR_HOUREN);

      /* Convert the struct tm format to RTC date register fields.
       *
       *   struct tm       CALALR register
       *   tm_mday   1-31  DATE   (1-31)
       *   tm_wday   0-6   DAY    (1-7)  **
       *   tm_mon    0-11  MONTH: (1-12)
       *   tm_year   *     YEAR   (0-99)
       *                   CENT   (19-20)
       *
       *  *Years since 1900
       * **Day of the week is not supported
       */

      calalr  = (rtc_bin2bcd(newalarm.tm_mday) <<
                 RTC_CALALR_DATE_SHIFT)  &
                 RTC_CALALR_DATE_MASK;
      calalr |= (rtc_bin2bcd(newalarm.tm_mon + 1) <<
                 RTC_CALALR_MONTH_SHIFT) &
                 RTC_CALALR_MONTH_MASK;
      calalr |= (RTC_CALALR_MTHEN | RTC_CALALR_DATEEN);

      /* Set the new date */

      putreg32(calalr, SAM_RTC_CALALR);

      /* Write the new time */

      putreg32(timalr, SAM_RTC_TIMALR);

      DEBUGASSERT((getreg32(SAM_RTC_VER) & RTC_VER_NVTIMALR) == 0);
      DEBUGASSERT((getreg32(SAM_RTC_VER) & RTC_VER_NVCALALR) == 0);

      rtc_dumpregs("New alarm setting");

      /* Enable alarm interrupts */

      putreg32(RTC_IER_ALREN, SAM_RTC_IER);
      ret = OK;
    }

  leave_critical_section(flags);
  return ret;
}
#endif

#endif /* CONFIG_RTC */
